#include <bits/stdc++.h>

using namespace std;

#define rep(i,x) for(int i=0;i<x;++i)
#define rep1(i,x) for(int i=1;i<=x;++i)
#define fst first
#define scd second
#define int long long

signed main()
{
    int n, a; cin >> n >> a;

    vector<int> x(n);

    int sum = 0;

    rep(i, n) {
        cin >> x[i];
        sum += x[i];
    }

    cout << (a * n == sum ? "YES" : "NO") << endl;
}